1. Field of the Invention
The present invention relates to a vacuum channel transistor and a manufacturing method thereof, and more particularly, to a vacuum channel transistor including a planar cathode layer formed of a material having a low work function or a planar cathode layer including a heat resistant layer formed of a material having a low work function, and a method of manufacturing the same.
2. Description of the Related Art
In a related art Spindt type vacuum channel transistor, when a high voltage is applied between the cathode electrode and a gate electrode, electrons are emitted through a surface of a pointed metal micro-tip of a cathode electrode. The emitted electrons are accelerated to reach the anode electrode by a voltage being applied to the anode electrode. In such a manner, a current flows in the related art Spindt type vacuum channel transistor.
In general, a voltage of 0.5 V/{acute over (Å)} or higher must be applied between the cathode and anode electrodes in order to emit sufficient free electrons from a metal surface in a vacuum. A spindt type cold cathode electrode emits electrons through field emission. For this emission of electrons, an electric field must be about 109 V/m or higher at a surface of the cold cathode electrode from which electrons are emitted.
The intensity of the electric field at the surface of the cathode electrode is defined as a value obtained by dividing a voltage between the cathode electrode and the anode electrode by a distance between the cathode and anode electrodes. Thus, in the case of using flat electrodes, to form an electric field of about 109 V/m between the electrodes, a voltage of about 106 V must be applied between the electrodes if the distance between the electrodes is about 1 mm. Also, even if the distance between the electrodes is about 1 μm, a voltage of about 1,000 V or higher must be applied.
In actuality, to achieve the electric field of about 109 V/m, a pointed micro-tip which is formed of metal such as silicon, molybdenum or tungsten is used. Due to geometrical effects of the micro-tip, the intensity of an electric field is high at an end of the micro-tip. Thus, by using the micro-tip, electrons can be emitted at a lower voltage than in the case of the flat electrodes.
However, the related art vacuum channel transistor including the metal micro-tip has the following limitations.
Ion sputtering and the like during an operation of the related art vacuum channel transistor may easily cause damage to the metal micro-tip. The damage to the metal micro-tip causes unstable operations of the vacuum channel transistor.
A process of forming uniform metal micro-tips having pointed shapes is very difficult. This significantly affects the image uniformity of a display device that adopts such vacuum channel transistors having the metal micro-tips.
In addition, since arc discharge is caused by a high electric field between the gate electrode and the micro-tip, the gate electrode and the micro-tip may be easily damaged. In actuality, the degree of vacuum of the related art vacuum channel transistor may be lowered during a processing process or an operation of the transistor, and an interval between electrodes is very short. For this reason, when impurities such as metal atoms are deposited between the electrodes, the arc discharge may easily occur, causing damage to the gate electrode or the micro-tip.